OK, we're set to go with the Thetford setup, with the one problem that using the longer new black connector entails. Son says the extra 7/8" length of the new one over the OEM Thetford (that is no longer available) will require a drop-down past the pan. Here is my solution for that small problem--an old aluminum 8"x8" baking pan. I found one at the thrift store with a large crimped edge; son unrolled that edge to form a flange to rivet the baking pan to the pan of the trailer. This is much better than the plastic piece that came from Airstream, which we threw away when we removed the old pan material.

Steve, we don't have a threaded connection, hence, the Thetford choice.

"I have found with almost every aspect of my resto there are many obstacles between ideas and execution." Ain't that the truth!

As we're nearing the home stretch on our camper, we're looking for a second early Argosy to work on, especially as we know so much more about the process. This is fun. I sure do like the idea of rehabilitating such a worthwhile product from the times past.

Oh yeah, baby. What a feelin'. It's only February, and you are in the running for mod of the year. And you know i can't just let you off without a photo request. Glad to know y'all got it working for you. I feel like I almost have to do another project myself and breeze through with a 'been there, done that' attitude. Keep up the good work.

Oddly enough I am dealing with the same issue now with my 1970 Caravel. The old Thetford drain valve was leaking. After some work removing it (rusted screws) I purchased a new Thetford valve and an ABS collector. As it turns out the collector attached to the drain valve now drops the gray water tie-in down lower than original tie-in. So, I have a greenish plastic black tank, the toilet flange was threaded so you would assume also the mounting plate is also threaded into the black tank. I can not be absolutely sure it is other than your knowledge that nothing bonds to that plastic. For my model year and black tank are you very confident that mounting flange is in fact threaded?

Greenish plastic is not necessarily polyethylene. You might have ABS...which can be bonded. Not sure. Please post pics so we don't make a mistake. Having a top flange threaded does not indicate the bottom is also threaded. The top is almost always threaded...even with ABS.

As it turns out, the original white ABS Thetford mounting flange at bottom of black tank was a slip fit with hose clamp. The tank is Polyethylene just has a green tint to it. I used a RotoZip to cut the four corners off of the mounting flange so that I could spin (still thought it was threaded in) the flange out of the tank due to the plywood surrounding the flange was cut tight around the flange. Once I cut the four corners I could feel around above the flange and discovered the hose clamp. Used the RotoZip again to cut the rusted screw and pulled out the flange.

I have ordered a new Valterra valve, valve flange and collector. Just hope the collector aligns up the 2" gray waste line once installed. Not such a difficult project but it does require a bit of research and this forum was very valuable information to have.

i HAVE a 1977 Argosy center bath 28' my dump vale comes stright down and with the thetford to valtera adapter and a 90 i am only 9 " off the ground, below the campground dump connection and we all know it don't run up hill
I am trying to change out all the thetford also

used thetford valve to black tank and glued and 3/4 "screws to attach a 3"90 with a 2" heal turned towards front of trailer then a street 90 and 2" of 3" pipe to connect a valterra bayonet
then connected a 2" valterra blade valve to the heal plumbed to gray tank now instead of straight down with an adapter its now turned out and gray tank dump is easy to get to it was under on frame works great